1. Field of the Invention
The invention relates to an apparatus that recognizes a lane marker on a road. More particularly, the invention relates to a lane marker recognition apparatus mounted in a vehicle.
2. Description of the Related Art
In recent years, lane marker recognition apparatuses which recognize a lane marker on a road on which a movable object such as a vehicle travels, based on a captured image of the road surface in the direction of travel, are being mounted in these movable objects (hereinafter simply referred to as vehicle). The lane marker recognition results of this kind of lane marker recognition apparatus are used as information for controlling the steering angle so that the host vehicle travels inside the running lane, for example. One example of this kind of lane marker recognition apparatus is the lane marker recognition apparatus described in Japanese Patent Application Publication No. 2003-271930 (JP-A-2003-271930) (hereinafter referred to as the “related art”).
In the related art, a lane marker on a road on which a host vehicle is traveling recognized based on a processed image which is a captured image of the road surface in the direction in which the host vehicle is traveling, which has been processed. More specifically, a horizontal row of pixels of the processed image are scanned, and the upper edge and lower edge where the luminance value changes abruptly at the boundary between the road surface and the lane marker are detected. When both the upper and lower edges are detected over the entire region of the processed image, the related art recognizes the center position between the detected upper and lower edges as the position of the lane marker.
However, various problems which are described below arise with the related art. That is, with the related art, when there is noise in the processed image, it affects the processed image in such a way that the luminance values of the captured image and the processed image change. The related art recognizes the position of the lane marker based on the processed image that has been affected by the noise, so the accuracy of the recognition results of the lane marker position decreases. When the accuracy of the recognition results of the lane marker position decreases, the accuracy of the information used for the purposes described above decreases.